The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with dis-closures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
Dynamic frequency scaling (also known as CPU throttling) is a technique whereby the frequency of a microprocessor may be automatically adjusted “on the fly” either to conserve power or to reduce the amount of heat generated by the chip. Dynamic frequency scaling is commonly used in laptops and other mobile devices, where energy comes from a battery and thus is limited. It is also used in quiet computing settings and to decrease energy and cooling costs for lightly loaded machines. Less heat output, in turn, allows the system cooling fans to be throttled down or turned off, reducing noise levels, and further decreasing power consumption. It is also used for reducing heat in insufficiently cooled systems when the temperature reaches a certain threshold. Due to static power consumption and asymptotic execution time the energy consumption of a piece of software shows convex energy behaviour, i.e. there is an optimal CPU frequency at which the energy consumption is minimal. Leakage current has become more and more important as transistor sizes have become smaller and threshold voltage levels lower. Dynamic frequency scaling reduces the number of instructions a processor is able to issue in a given period of time, thus reducing performance.